420 MPa grade low yield strength ratio resistance to marine atmospheric corrosion bridge steel and production method thereof

Abstract

The invention discloses a steel 420MPa grade low yield ratio marine atmospheric corrosion resistant bridge and a production method thereof, the steel comprises the following chemical components in percentage by mass: 0.04-0.20% of C, 0.15-0.45% of Si, 0.85-1.80% of Mn, 0.015-0.050% of Alt, 2.50-4.75% of Ni, 0.20-0.60% of Cu, 0.020-0.080% of Nb, 0.015 to 0.036 percent of Ti, 0.0020 to 0.0050 percent of Ca, less than or equal to 0.020%of P, less than or equal to 0.002%of S, less than or equal to 0.004%of N and the balance of Fe and other inevitable impurities; after the steel of passes the composition design, the inclusion control, the controlled rolling , the controlled cooling and heat treatment, the steel has the advantages of high strength, low yield strength, and can be used for manufacturing various bridges under the ocean atmospheric environment, and the safety of use is greatly improved.

Description

technical field [0001] The invention relates to the technical field of iron and steel materials, in particular to a 420MPa low-yield ratio steel for marine atmospheric corrosion-resistant bridges and a production method thereof. Background technique [0002] In recent years, high-performance bridge steel has made great progress. More and more long-span steel bridges are under construction or have been completed. However, weather-resistant bridge steel specially used in marine and atmospheric environments still has low strength, high yield ratio and Poor marine corrosion resistance and other issues. The marine atmospheric environment includes the ambient atmosphere mainly polluted by chlorides such as the offshore, coastal areas and the atmosphere of the salt area (the area where the soil type is saline soil or the area exposed to deicing salt). The marine atmospheric environment means that the steel is more Therefore, the bridge steel used in the marine and atmospheric envi...

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Problems solved by technology

[0005] The purpose of the present invention is to provide a 420MPa grade low yield ratio corrosion-resistant bridge for marine and atmospheric environments in view of the problems that the existing steel grades have high yield ratio, poor weather resistance and yield ratio matching, and cannot be applied to marine and atmospheric environments. Steel and its production method, adopting the method of the present invention can obtain the steel for bridges with a yield strength ratio lower than 0.85 and good toughness and tensile properties resistant to marine atmospheric corrosion

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